According to Conservative members of the group, the MPs would have met senior Sri Lankan government ministers and officials, including President Mahinda Rajapaksa, who stands accused of command responsibility for war crimes.

It was getting too complicated. It was going to be a bun-fight. What, with you lot getting involved and with the whole Maria Miller thing, it was all just too much. Ian Liddell-Grainger MP

The charity denies having any political agenda and told Channel 4 News it is “entirely independent of the Sri Lankan government.”

Conservative Party members of the parliamentary group said they are furious with two Labour members who, they claim, pulled the plug on their participation in the Easter-recess ‘fact-finding’ visit late on Wednesday night.

Unusually, the group had been planning to travel to the country without informing the All-Party Parliamentary Group on Sri Lanka of their proposed trip.

‘Complicated’

Channel 4 News understands the sudden cancellation of their participation followed the intervention of a senior Labour front-bencher who strongly objected to what would have been a highly-controversial visit.

One of the Conservative members of the group, Ian Liddell-Grainger MP – who was to have been joined by his wife – told Channel 4 News: “It was getting too complicated. It was going to be a bun-fight. What, with you lot getting involved and with the whole Maria Miller thing, it was all just too much.”

The group of MPs was to have flown direct to Colombo from London Gatwick at 2.25pm on Thursday. A Labour Party spokesperson denied any knowledge of the proposed trip, however, and stated: “No Labour MP is taking part in a visit to Sri Lanka.”

They decided not to go for whatever reason and that spoiled the trip.Laurence Robertson MP

When pressed, the spokesman repreatedly refused to confirm whether any Labour MP had ever planned to go on the trip.

“I am really disgusted that they are saying this,” said Laurence Robertson, the Conservative MP for Tewkesbury, who was to have led the group. “I have their tickets!”

The Labour MPs who were due to have joined the week-long trip were Sharon Hodgson, MP for Washington and Sunderland West – along with her husband – and Stephen Hepburn, MP for Jarrow. Ms Hodgson is shadow minister for equalities – and as such, was, until Wednesday, Maria Miller’s opposite number.

Channel 4 News has obtained copies of their tickets, confirming Mr Robertson’s account and showing that the Labour MPs were due to travel business class.

Neither MP returned calls or responded to emails asking for comment.

“They decided not to go for whatever reason and that spoiled the trip,” said Mr Robertson, who was also to have been accompanied on the trip by his partner.

‘Beautiful island’

The Democratic Unionist MP for North Antrim, Ian Paisley Jr, was also to have been on the planned trip, although he and his wife would have left a day later and spent 10 days in Sri Lanka. Mr Paisely was apparently unaware that the trip had been cancelled until contacted by Channel 4 News.

He expressed disappointment that he would not have the chance to draw on his personal experience in post-conflict reconciliation efforts in the north of Ireland while in Sri Lanka.

The MP has participated in several parliamentary debates in which he has defended the Sri Lankan regime, supporting its “Lessons Learnt and Reconciliation Commission.” The government claimed the commission investigated the final years of Sri Lanka’s 26-year-long civil war. It was dismissed by leading international human rights groups as a whitewash, designed to exonorate the government of any responsibility for alleged war crimes.

Siobhain McDonagh MP, a critic of the Sri Lankan regime, criticised her colleagues’ planned trip. “I feel this visit would have been completely inappropriate,” she said. “I am alarmed by the lack of democracy and increasing repression in Sri Lanka.” She added: “But let’s face it, it is a beautiful island and you could persuade yourself of anything.”

Last November, during the Commonwealth summit in Sri Lanka, the prime minister banned Conservative MPs from accepting trips financed by the Sri Lankan government because of growing concern over the regime’s lobbying tactics. Mr Robertson insisted that the government of Sri Lanka was not involved in the funding of their proposed trip, and had it been, he said, the MPs would not have gone.

David Cameron has been vociferous in his support for an international investigation into alleged war crimes and human rights abuse in Sri Lanka and the British government co-sponsored last month’s UN Human Rights Council resolution which mandated a formal inquiry. The Labour Party has consistently called for an international investigation.

Mr Cameron joined the cricketer Mutthiah Muralitharan (pictured, above) – better known simply as Murali – for an event with his charity during the Commonwealth summit last November. Murali’s charity promotes reconciliation through social projects.

Murali later insisted that Mr Cameron had been “misled” about the human rights situation in his country while the prime minister toured the former warzone in the north.

It is Murali’s charity, the Foundation of Goodness, that was going to pay for the trip by the MPs who were to have left on Thursday. Contacted by Channel 4 News, Kushil Gunasekera, its co-founder, said this “was the first trip of its kind that the foundation had organised.”

Jan Jananayagam, from the campaign group Tamils Against Genocide, said: “The Sri Lankan government has always used cricket and its leading cricketers, particularly Murali, because of his Tamil origins, to whitewash the allegations against of it mass atrocities. It would seem this proposed trip was no exception.”

She added that as a result of growing controversy over Sri Lankan government-funded trips to the country, “any visit would need to be arranged via a third party beholden to the government. Murali unfortunately is one of those.” Murali’s charity denies the allegation.

The Foreign and Commonwealth Office was aware of the MPs’ proposed trip and a spokesperson said the British high commissioner had offered to brief members of the group on arrival.

A spokesperson from No 10 Downing Street said the prime minister had not been involved in the decision to cancel the trip. Conservative Central Office did not respond to requests for a comment; neither did the Sri Lankan High Commission.